- Electrochemical direct carboxylation of benzyl alcohols having an electron-withdrawing group on the phenyl ring: One-step formation of phenylacetic acids from benzyl alcohols under mild conditions
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Electrochemical direct carboxylation of benzyl alcohols having an electron-withdrawing group on the phenyl ring was successfully carried out by constant current electrolysis using an undivided cell equipped with a platinum plate cathode and a magnesium rod anode in DMF in the presence of carbon dioxide. Reductive cleavage of the C-O bond followed by fixation of carbon dioxide efficiently took place at the benzylic position without any additive to give the corresponding phenylacetic acids in good yields in one step under neutral and mild conditions.
- Senboku, Hisanori,Yoneda, Kenji,Hara, Shoji
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p. 6772 - 6776
(2016/01/30)
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- Electrochemical reduction of methyl 2-bromomethylbenzoate at carbon cathodes in dimethylformamide containingwater
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Cyclic voltammetry and controlled-potential electrolysis have been employed to examine the electrochemical reduction of methyl 2-bromomethylbenzoate at carbon cathodes in dimethylformamide (DMF) containing tetramethylammonium tetrafluoroborate (TMABF4). A cyclic voltammogram for the reduction of the substrate exhibits one irreversible cathodic wave with a peak potential of -1.45 V vs. SCE, which is due to the two-electron cleavage of the benzylic carbon-bromine bond. The corresponding reductive peak current also increases incrementally with the amount of water in DMF. Bulk electrolyses of methyl 2-bromomethylbenzoate have been carried out at -1.85 V vs. SCE with different concentrations of water in the solvent. The reduction process involves carbanion intermediates to afford various products including phthalide, which is generated via intramolecular cyclization that is affected by the presence of water. Detailed mechanism for the electrochemical reaction is proposed and further studied by isotope incorporation experiment.
- Allen, Caroline R.,Brown, Drew K.,Potts, Jessica L.,Ji, Chang
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p. G3069-G3072
(2013/07/05)
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- Practical and chemoselective reduction of acyl chloride to alcohol by borohydride in aqueous dichloromethane
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A simple methodology for the reduction of acid chlorides to their corresponding alcohols has been developed. Various carboxylic acids were converted to alcohols in excellent yields using NaBH4-K2CO3 in a mixed solvent system of dichloromethane and water (1:1) in the presence of a phase-transfer catalyst at low temperature. The importance of the work is its simplicity, selectivity, excellent yield, and very short reaction time. This new reduction condition has proved to be an excellent chemoselective method for a range of acid chlorides in the presence of various functional groups.
- Rajan, Ramya,Badgujar, Sachin,Kaur, Kamaljit,Malpani, Yashwardhan,Kanjilal, Pranab R.
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experimental part
p. 2897 - 2907
(2010/11/18)
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- Reduction of carboxylic acids by tetraalkyl ammonium borohydride
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Tetraalkylammonium borohydride reduces carboxylic acids to the corresponding alcohols in good yields utilizing only stoichiometric quantities of hydride and also in the absence of any Lewis acids.
- Narasimhan,Swarnalakshmi,Balakumar
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p. 941 - 946
(2007/10/03)
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- Chemoselectivity of tetrabutylammonium borohydride towards bifunctional esters
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Chemoselective reduction of functional groups in the presence of esters is observed with tetrabutylammonium borohydride in chloro solvents.
- Narasimhan,Swarnalakshmi,Balakumar,Velmathi
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p. 1321 - 1322
(2007/10/03)
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- Selective reduction of mixed anhydrides of carboxylic acids to alcohols using borohydride exchange resin (BER)-nickel acetate
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Mixed anhydrides of carboxylic acids have been selectively reduced to alcohols with borohydride exchange resin-nickel acetate under mild conditions and in good yields.
- Bandgar,Modhave,Wadgaonkar,Sande
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p. 1993 - 1994
(2007/10/03)
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- Correlation Analysis of Reactivity in the Oxidation of Substituted Benzyl Alcohols by Pyridinium Hydrobromide Perbromide
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Oxidation of monosubstituted benzyl alcohols by pyridinium hydrobromide perbromide (PHPB) leads to the formation of the corresponding benzaldehydes.The reaction is first order with respect to PHPB.Michaelis-Menten-type kinetics were observed with respect to he alcohol.The oxidation of α,α-dideuteriobenzyl alcohol indicated the presence of a substantial kinetic isotope effect.The rates of oxidation of meta- and para-substituted benzyl alcohols were correlated in terms of Taft's and Swain's dual substituent-parameter equations.The rates of the meta compounds correlated best with Taft's ?1 and ?0R values whereas the para-compounds showed an excellent correlation with Taft's ?1 and ?R + constants.The rates of the otho-substituted alcohols showed very good correlation with Charton's triparametric equation.The rate increased with an increase in the polarity of the solvent.A mechanism involving a rapid reversible formation of an intermediate complex and its subsequent decomposition in the rate-determining step has been proposed.
- Suri, Deepa,Banerji, Kalyan K.,Kothari, Seema
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p. 1734 - 1758
(2007/10/03)
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- A convenient and mild procedure for the preparation of hydroxyesters from lactones and hydroxyacids
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An alcoholic solution of lactones and hydroxyacids stored on Amberlyst-15 results in the formation of corresponding hydroxyesters in high yields.
- Anand,Selvapalam
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p. 2743 - 2747
(2007/10/02)
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- Preparation of 1-Ethoxyisobenzofuran. Mechanistic Aspects of the Meerwein Ortho Ester Reaction
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The reaction of O-ethylphthalidium tetrafluoroborate (1) with excess NaOCH3 in CH3OH gives ortho ester 4 as the major product.The mechanism of formation of this solvent-derived material is explored.A plausible intermediate, 1-ethoxyisobenzofuran (8), has been prepared and isolated in solution; 8 reacts readily with, e.g., CH3OD to give the mixed ortho ester 5 contaning ca. one deuterium/mole.This indicates that 8 reacts by rate-determining proton transfer, followed by collapse of the ion pair to give 5.On these and other grounds, 8 is ruled out as an intermediate in the reaction of 1 leading to 4.A mechanism for the latter process consistent with all observations is presented, involving rapid consumption of local alkoxide ion concentration followed by rapid exchange with solvent and eventual neutralization by diffusion of alkoxide from the bulk medium.
- Mir-Mohamad-Sadeghy, Bagher,Rickborn, Bruce
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p. 1477 - 1481
(2007/10/02)
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